Mesh doesn't follow armature
Until the day arrives that we all have super computers... the meshes used for sculpting are not the ones used for animating. There are too many vertices which makes it cumbersome to rotate around, let alone animate. The automatic weights are not finding a solution - perhaps because of the high vertex count - and though you can manually add weight I don't think this is going to bring much joy.

My suggestion is to retopo a 'lighter' version which will be easier to work with.

Update: In response to Vlads comment below. The greatest concentration of verts are in the face. Selecting the face and AltP to separate it from the rest of the body. The headless body accepts the automatic bone weights and can be deformed by the armature. The obvious problem are the gaps that will form between the two objects.

It is always easier to talk after the fact but... finding a pose with a simpler mesh, earlier in the process, would have saved a lot of trouble.